The correct answer is - When two tectonic plates move in opposite directions, it causes magma to rise, creating a new seafloor.
On the places where there's a divergent plate boundary, thus the plates are moving away from one another, the space they leave in between is becoming thinner and softer. Because the crust becomes much easier to crack, the high temperatures high pressure, and magma, manage to penetrate easily through it. As the magma reaches the seafloor, it cools of and creates new rocks, thus new seafloor, which is manifested with mid ocean ridges. As more and more magma comes out, more and more new crust will be forming.
